Re: kern/54419: mbuf leak when deleting route

[Ryota Ozaki <ozaki.ryota%gmail.com@localhost>]

The following reply was made to PR kern/54419; it has been noted by GNATS.

From: Ryota Ozaki <ozaki.ryota%gmail.com@localhost>
To: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/54419: mbuf leak when deleting route
Date: Thu, 1 Aug 2019 15:32:13 +0900

 On Mon, Jul 29, 2019 at 5:35 PM <sc.dying%gmail.com@localhost> wrote:
 >
 > >Number:         54419
 > >Category:       kern
 > >Synopsis:       mbuf leak when deleting route
 > >Confidential:   no
 > >Severity:       serious
 > >Priority:       high
 > >Responsible:    kern-bug-people
 > >State:          open
 > >Class:          sw-bug
 > >Submitter-Id:   net
 > >Arrival-Date:   Mon Jul 29 08:35:00 +0000 2019
 > >Originator:     sc.dying%gmail.com@localhost
 > >Release:        NetBSD 8.99.51
 > >Organization:
 > >Environment:
 > System: NetBSD  8.99.51 NetBSD 8.99.51 (GENERIC) #0: Sun Jul 28 17:41:21 UTC 2019  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64 x86_64
 > >Description:
 >
 > An mbuf goes somewhere when deleting a route on -current/amd64 and -8.1/amd64.
 >
 > When you delete a route using route command, it is deleted successfully, but
 > mbuf usage of netstat -m gains 1.
 > See How-To-Repeat for detail.
 >
 > I saw same problem on NetBSD-8.1/amd64, too.
 >
 > >How-To-Repeat:
 >
 > After boot single, I typed following commands.
 >
 > # uname -ap
 > NetBSD  8.99.51 NetBSD 8.99.51 (GENERIC) #0: Sun Jul 28 17:41:21 UTC 2019  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64 x86_64
 > # ifconfig lo0 127.0.0.1
 > # route add 192.168.0.1 127.0.0.1
 > add host 192.168.0.1: gateway 127.0.0.1
 > # netstat -m
 > 0 mbufs in use:
 > 0 calls to protocol drain routines
 > # route delete 192.168.0.1
 > delete host 192.168.0.1
 > # netstat -m
 > 1 mbufs in use:
 >         1 mbufs allocated to data
 > 0 calls to protocol drain routines
 > # sh -c 'i=0; while [ $i -lt 10000 ]; do route -q add 192.168.0.1 127.0.0.1; route -q delete 192.168.0.1; i=$((i+1)); done'
 > # netstat -m
 > 10001 mbufs in use:
 >         10001 mbufs allocated to data
 > 0 calls to protocol drain routines
 > #
 
 The leak occurs if there is no listener of routing sockets.  That's the
 reason the single user mode is needed and we don't observe the leak
 normally.
 
 >
 > >Fix:
 >         Yes, please.
 
 The below patch fixes the leak.
 
 I guess it's a typo.  Should we disallow normal users of m_freem to
 use m_free accidentally by say renaming it to _m_free or something?
 
 Thanks,
   ozaki-r
 
 diff --git a/sys/net/raw_usrreq.c b/sys/net/raw_usrreq.c
 index 24185c17939..19d96dcb82b 100644
 --- a/sys/net/raw_usrreq.c
 +++ b/sys/net/raw_usrreq.c
 @@ -110,7 +110,7 @@ raw_input(struct mbuf *m0, struct sockproto
 *proto, struct sockaddr *src,
         }
         if (last != NULL) {
                 if (sbappendaddr(&last->so_rcv, src, m, NULL) == 0) {
 -                       m_free(m);
 +                       m_freem(m);
                         soroverflow(last);
                 } else
                         sorwakeup(last);